1. Field of the Invention
The present invention relates to an information recording system, and more particularly a system for recording computer input information upon a microfilm as optical digital information.
2. Description of the Prior Art
The data processing capabilities of the computers have been remarkably increased because of the improvements of the hard and soft wares, but the input-output devices whose data processing speeds are considerably lower than the speeds of the central processing units so that they present the serious obstacles to the computerization. Furthermore the recording density of the punched cards, punched paper tape and the like is low so that the large storage of these recording media and the protection thereof against destruction also present serious problems.
The computer output microfilmers have been recently developed so that the output data processing speed has been considerably increased, but the conventional punched card readers, paper tape readers or magnetic film readers are still used and the input devices so that the reading speed is considerably lower than the data processing speeds of the central processing units. The improvement of the reading speed of these input devices is limited because they incorporate the mechanical components. Furthermore the recently developed large scale computers make it necessary to record information at a high density, but the conventional input recording media such as punched cards, paper tape or magnetic tape have a very low recording density so that a large space is required for the storage of these recording media especially in a computer center where a large number of programs are stored.
To overcome the above problems, there has been proposed a method in which the data recorded upon a punched card are directly projected upon a microfilm F by utilizing a rotary camera as shown in FIG. 1, but the recording density cannot be improved beyond a certain level. Furthermore the accuracy of the position of data recorded within a frame of the microfilm is poor so that the recorded data cannot be read out with a required degree of accuracy.
The optical digital signals recorded upon the film may be read out in time series by an optical reader such as a flying spot scanner. In this case, timing or sync signals must be utilized in order to indicate the positions of the optical digital signals. Since the relation between the timing or sync signals and the time-sequence output signals of the optical reader reaches the maximum electrically and mechanically stable level of the optical reader as the density of the optical digital signals recorded upon the film is increased, the linear relation between the timing or sync signals and the readout signals is lost so that the correct reading of the optical digital signals becomes impossible.